1. Field of the Invention
The present invention relates to a heat exchanger carrying out heat exchange between a first fluid and a second fluid, and a box-type cooling unit including the heat exchanger.
2. Description of Related Art
Conventionally, a cross-flow type heat exchanger J1 shown in FIG. 30, and a counter-flow type heat exchanger J2 shown in FIG. 31 are known as a heat exchanger carrying out a heat exchange between a high temperature air and a low temperature air. In the cross-flow type heat exchanger J1, the high temperature air and the low temperature air perpendicularly cross to heat exchange with each other. In the counter-flow type heat exchanger, the high temperature air and the low temperature air flow in opposite directions to heat exchange with each other.
The cross flow type heat exchanger J1 is inferior to the counter-flow type heat exchanger in view of a heat exchanging efficiency.
In the counter-flow type heat exchanger, as shown in FIG. 31, because the cross sectional area of each air passage is small and a corrugated fin J3 is disposed inside the air passage, the pressure loss of the air is increased. Thereby, a fan generating the air flow is large, and high power for driving the fan is also required.
Further, in the counter-flow type heat exchanger, because the air introduction area of the corrugated fin 3 is small, foreign matter such as dust tends to choke the air passage.